Rotary screen printing machine with internal squeegee

ABSTRACT

A rotary screen printing machine wherein the rotary screen rises from the printing operation position at the time of termination of the printing operation and at this risen position the rotary screen is driven and rotated independently of the printing belt, whereby an undesired phenomenon that at the time of stoppage of the printing operation a printing paste or ink flows out through the screen onto the material to be printed or the printing belt and causes contamination of the material to be printed upon can be effectively prevented.

United States Patent [1 1 Ichinose 1 Nov. 27, 11973 [54] ROTARY SCREENPRINTING MACHINE 3,572,240 3/1971 Bohm lOl/116 WITH INTERNAL SQUEEGEE3,420,167 1/1969 Van Der Winden 101/1 16 [76] Inventor: Shiro Ichinose,11-8, l-chome, FOREIGN PATENTS OR APPLICATIONS Shinohara Kita-machi,266,650 12/1966 U.S.S.R 101/1 16 Kobe, Japan 2 Filed; 9, 1972 PrimaryExaminerRobert E. Pulfrey Assistant Examiner-Eugene H. Eickholt [21]Appl' 233038 Att0rneyE. F. Wenderoth et a1.

[30] Foreign Application Priority Data [57] ABSTCT 4 Dec 15? 1971 Japan6/101042 A rotary screen printmg machine wherein the rotary [52] U S Cl101 A19 101 89 screen rises from the printing operation position at the[51] a 13/00 time of termination of the printing operation and at [58]Fie'ld [114420 this risen position the rotary screen is driven and ro-129 181 tated independently of the printing belt, whereby an 1 undesiredphenomenon that at the time of stoppage of [56] References Cited theprinting operation a printing paste or ink flows out through the screenonto the material to be printed or UNITED STATES PATENTS the printingbelt and causes contamination of the ma- 3,291,044 12/1966 Van DerWinden 101/118 terial to be printed upon can be effectively preventecL3,585,930 6/1971 Bohm 101/116 3,565,002 2/1971 Boehm 101/116 7 Claims, 6Drawing Figures 15/ 33 22 [2 12% 2l 2O 1 p o) m o m o m m ,c; O

P'ATENIEDHnv 27 1975 SHEET 3n; 4

ROTARY SCREEN PRINTING MACHINE WITH INTERNAL SQUEEGEE This inventionrelatesto a rotary screen printing machine. More particularly, theinvention relates to a rotary screen printing machine wherein the rotaryscreen rises from the printing operation position at the time oftermination of the printing operation and at this raised position therotary screen is driven and rotated independently of the printing belt,whereby the effluence of a printing paste or ink through'the screen canbe effectively prevented at the time of stoppage of the printingoperation.

A rotary screen printing machine of the type that has heretofore beenused widely comprises pulleys provided on both sides of the printingoperation zone, at least one of which is driven, a printing beltsupported and driven by said pulleys, which is adapted for supporting amaterial to be printed and transporting it to the printing operationzone, a squeegee member mounted in the interior of the rotary screen forsqueezing a printing paste or ink onto the material to be printedthrough said screen, anda drive mechanism for driving the rotary screenat a speed synchronized with the speed of the printing belt.

In the known rotary printing machine, when one printing cycle has beenterminated, the color change, the design exchange and other operationsare conducted after lowering of the printing belt from the printingoperation position or raising of the rotary screen from the printingoperation position, or without such lowering or rising of the printingbelt or rotary screen. However, in the known rotary screen printingmachine there is a great problem at the time of stoppage of the printingoperation the printing paste or ink is flowing out onto the printingbelt or the material to be printed which is supported on the printingbelt and consequently causes contamination of the printing belt and thematerial to be printed no means capable of preventing effectively thisefiluence of the printing ink from the screen has been found.Accordingly, in the conventional printing operation, a saucer forreceiving the paste or ink is inserted below the rotary screencoincidentally with stoppage of the printing operation. However, suchoperation requires additional manual labor and is troublesome. Further,such operation is still insufficient for preventing completelycontamination caused by the effluence of the printing ink.

l have now arrived empirically at the knowledge that in the rotaryscreen printing machine of the abovementioned type, the tendency of theprinting ink or paste to flow out through the screen at the time ofstoppage of the printing operation can be greatly inhibited by liftingup the rotary screen from the printing operation position at the time ofstoppage of the printing operation and driving and rotating it at thisraised position independently of the printing belt, with the consequencethat contamination of the printing belt or the material to be printedwhich is supported on the belt caused by effluent paste orink can beeffectively prevented.

whereby the effluence of the printing paste or ink through the screencan be effectively prevented at the time of stoppage of the printingoperation.

My invention further seeks to provide a rotary screen printing machinewhereinwhen the rotary screen is at the printing operation position, theforce for driving the rotary screen is transmitted by a first drivemechanism for driving the printing belt and the rotary screen at asynchronized speed, and when the rotary screen is at the position inwhich it has been lifted up from the printing operation position, theforce for driving the rotary screen is transmitted by a second drivemechanism independent of the first drive mechanism, in each case thetransmission of the force for driving the rotary screen being effectedthrough an idle gear mounted on a supporting shaft for supporting therotary screen for vertical movement, whereby the rotary screen can bedriven and rotated either during the printing rotary screen-at a speedsynchronized with the speed of the printing belt, wherein a bearingdevice for the rotary screen is mounted on a supporting member, one endof which is pivoted on a supporting shaft and the other end of which isattached to a lifting device, a screen gear fitted on the rotary screenis driven by a screenternatively with a first drive mechanism fordriving the Accordingly, it is a primary object of my invention torotary screen at a speed synchronized with the speed of the printingbelt and a second drive mechanism inde pendent of and first drivemechanism, whereby at the time of stoppage of the printing operation therotary screen is caused to rise from the printing operation position andat this raised position the rotary screen is driven and rotatedindependently of the printing belt.

This invention will be explained more fully by reference to theaccompanying drawings, which illustrate an embodiment of the rotaryscreen machine of this invention.. FIGS. LA and 1-8 are side viewsillustrating the drive mechanisms of the rotary machine of thisinvention, FIG. A-l showing the positions of the parts during theprinting operation and FIG. l-B showing the positions of the parts atthe time of stoppage of the printing operation.

FIGS. Z-A and 2-8 are side views illustrating the arrangement of thelifting device of the rotary screen printing machine illustrated inFIGS. l-A and ll-B, FIG. 2-A showing the positions of the parts duringthe printing operation and FIG. Z-B showing the positions of the partsatthe time of stoppage of the printing operation.

P16. 3 is an enlarged partial side view illustrating the supportingmechanism of the bearing device in the rotary screen printing machine ofthis invention.

FIG. 4 is a top plan view illustrating the supporting mechanism of thebearing device shown in FIG. 3.

ln FIGS. l-A and 1-8, on opposite ends of a frame 1, namely at the endsof the printing operation zone, a drive pulley 2 and an idle pulley 3are mounted, and a printing endless belt 4 is stretched between driveand idle pulleys 2 and 3, and supported and driven by these pulleys 2and 3. For driving the drive pulley 2, a drive shaft 3 on which thedrive pulley 2 is fixed has a sprocket or pulley 6 mounted thereon, andthe driving force supplied by a motor M is transmitted to the drivepulley 2 by means of a chain 9 (or drive belt 9) extending between adrive sprocket 8 (or pulley 8) of a reduction gear 7 mounted on themotor M and said sprocket 6 (or pulley 6).

Above the idle pulley 3, a material 10 to be printed, such as a cloth orfabric, is fed onto the upper surface of the printing belt 4, andsupported and transported to the printing operation zone by the printingbelt 4. The material 10' which has been printed is separated from theupper surface of the printing belt 4 above the drive pulley 2, followingwhich the material 10' is forwarded to the drying or winding step. Abovethe idle pulley 3, a press roller 11 is provided so that it is incontact with the printing belt 4 travelling in the idle pulley 3, andthe material 10 to be printed is fed between the press roller 11 and theprinting belt 4 by a guide roller 12 mounted upstream of the pressroller 11. Above the drive pulley 2 there is mounted a guide roller 13to separate from the printing belt 4 the material 10' which has beenprinted and forward it to the subsequent treatment zone.

Above the printing operation zone, namely above the printing belt 4stretched between the drive and idle pulleys 2 and 3, one or a pluralityof rotary screens 14 are disposed, in the interior of which a squeegeemember 15 is provided for squeezing a printing ink or paste onto thematerial 10 to be printed through said screen. During the printingoperation (FIG. l-A), the rotary screen 14 contacts with the material 10to be printed, which is supported on the printing belt 4, and is drivenat a speed synchronized with the travelling speed of the printing belt4. Thus, an image of a pattern corresponding to that on the rotaryscreen 14 is printed and fonned on the material 10 to be printed. In thecase of a plurality of rotary screens, their position and phase are soarranged that a desired pattern or combination of colors can be formedon the material 10 to be printed.

The prominent characteristic feature of this invention is that thebearing device for each rotary screen 14 is mounted on a supportingmember, one end of which is pivoted on a supporting shaft and the otherend of which is attached to a lifting device, the screen gear fitted onthe rotary screen 14 is engaged with a screendriving gear through anidle gear fitted on the supporting shaft, and said screen-driving gearis connected alternatively with the first drive mechanism for drivingthe rotary screen 4 at a speed synchronized with the speed of theprinting belt 4 and the second drive mechanism independent of the firstdrive mechanism.

In the printing machine of this invention, because of thischaracteristic construction it is possible to drive the rotary screen 14at the printing operation position at a speed synchronized with thespeed of the printing belt 4 during the printing operation and to driveand rotate the rotary screen 14 at the position lifted from the printingoperation position independently of the printing belt 4 at the time ofstoppage of the printing operation, whereby effluence of a printingpaste or ink through the screen can be effectively prevented.

The above characteristic feature will now be described in detail withreference to FIGS. 2-A and 2-B and FIG. 3. As can be seen from FIG. 3, abearing device 16 for each rotary screen 14 is mounted in a supportingmember 21 pivoted at one end 17 on a supporting shaft 18, and the otherend 19 is attached to a lifting device 20. The supporting shaft 18 issupported rotatably on the frame 1. Thus, the supporting member 21 canoscillate around the supporting shaft 18 as the center, and withoscillation of the supporting member 21, also the rotary screen 14 canoscillate around the supporting shaft 18 as the center. The liftingdevices 20 are mounted on a lift frame 22, and an optional mechanism forvertically moving the lift frame 22 is mounted on the frame 1. As can beseen from FIGS. 2-A and 2-B, racks 23 are provided on the lift frame 22extending in the vertical direction, and pinions 24 are mountedrotatably at positions engaged with the racks 23. One end of anoscillating arm 25 is fixed to each pinion 24, and the other end of theoscillating arm 25 is oscillatably mounted on a silde shaft 26. One endof the slide shaft 26 is attached to an am 28, one end of which isoscillatably fitted on a shaft 27. The other end of the arm 28 isconnected with a piston member 30 of a pressure cylinder 29. When theslide shaft 26 is shifted in the right direction by introducing into thepiston member 30 a pressurizing fluid such as compressed air or oil, thepinion 24 is rotated is the counter-clockwise direction and the racks 23are shifted upwardly, whereby the lift frame, the lifting member and therotary screens 14 are lifted, in turn, from the printing operationposition shown in FIG. 2-A to the upper position shown in FIG. 2-B. Thelifting and lowering of the lift frame 22 may be accomplished byemploying a known hydraulic machine instead of the lifting and loweringmechanism shown in FIGS. 2-A and 2-B.

In this invention, it is preferred that, as is illustrated in FIG. 2,the squeegee members 15 be supported by the lift frame 22. If suchmethod of supporting the squeegee members 15 is adopted, the squeegeemembers 15 are shifted by a distance corresponding to the liftingdistance (/1 of the lift frame 22, while the screens are lifted only adistance expressed by the following equation:

wherein h stands for the distance the lift frame 22 is raised, kindicates the distance the screen 14 is raised, d designates thedistance between the supporting shaft 18 and the lifting device 20, and11, represents the distance from the supporting shaft 18 to the point atwhich each screen 14 comes into contact with the corresponding squeegeemember 15. Accordingly, with the rise of the lift frame 22, between theinner surface of each screen 14 and the end point of the squeegee member15 there is formed a space expressed by the following formula:

Therefore, at the risen position the rotary screens 14 can be driven androtated without coming into contact with the squeegee member 15, withthe result that the problem of bleeding of the printing paste or ink canbe solved more effectively.

As is illustrated in FIGS. 1-A and l-B, a screen gear 31 is attached tothe end portion of each rotary screen 14, and the gear 31 is engagedwith an idle gear 32 fitted on the corresponding supporting shaft 18. Asis illustrated in FIGS. 3 and 4, a shaft 33A is mounted on each liftingmember 20, and on both ends of the shaft 33A there are mounted gears 33so that the gears 33 are engaged with screen gears 31 mounted on bothends of the rotary screen 14. With such a construction, by means of theidle gear 32, the drive force transmitted to one end of the screen 14 isconveyed to the other end of the screen 14 through the screen gear 31 onone end, the gear 33 on one end, the shaft 33A, the gear 33 on the otherend and the screen gear 31 on the other end. By adopting such aconstruction, an undesired phenomenon of twisting of the screen can beprevented effectively. Below the idle gear 32 fitted on each supportingshaft 18, a screen-driving gear 34 is provided so that it is engagedwith said idle gear 32. A helical worm gear 35 is fixed to eachscreen-driving gear 34, and is meshed with a helical gear 37 attached toa screendriving shaft 36 extending in the longitudinal direction of theframe 1. By rotation of the screen-driving shaft 36, the screen-drivinggears 34 are driven through the engagement between the helical gears 37and the helical worm gears 35, and the drive force of the screendrivinggears 34 is conveyed to the screen gears 31 through the idle gears 32,whereby the rotary screens 14 can be driven and rotated smoothlyirrespective. of the position of the screens 14.

One end of the screen-driving shaft 36 is connected via a magneticclutch or other known clutch M1 to a first drive mechanism, and theother end of the shaft 36 is connected via a magnetic clutch or otherknown clutch M2 to a second drive mechanism. Any mechanism capable ofdriving the rotary screens 14 at a speed synchronized with the speed ofthe printing belt 4 may be used as the first drive mechanism. Forinstance, the drive mechanism M for the drive pulley 2 driving theprinting belt 4 may be utilized also as the first drive mechanism.However, in this invention it is preferred that the idle pulley 3 of theprinting belt 4 be used as the first drive mechanism for driving androtating the rotary screens 14 at a speed synchronized with the speed ofthe printing belt 4.

For attainment of the above, in FIG. 1-A, a spur drive gear 39 is fixedon the shaft 38 on which the idle pulley 3 is fixed, an idle gear 40 ismounted so that it is engaged with the drive spur gear 39, and anexchangeable change gear 41 is mounted so that it is engaged with theidle gear 40. A bevel gear (not shown) is fixedto the change gear 41.From this bevel gear the drive force is transmitted through a bevel gear42, another bevel gear 43 connected to the bevel gear 42, and stillanother bevel gear 44 to a drive shaft 45, one end of which is fixed tothe bevel gear 44. To the other end of the drive shaft 45 is fixed aspur gear 46 which is engaged with a spur gear 47 mounted freely movablyon the screen-driving shaft 36. The spur gear 47 fitted on the shaft 36and the magnetic or other known clutch M1 attached to the shaft 36 areso arranged that when the clutch M1 is actuated, the shaft 36 is drivenand rotated by the drive force conveyed to the spur gear 47 and when theclutch M1 'is not actuated, the spur gear 47 and the screen-drivingshaft 36 are rotated independently of each other. Thus, when the clutchM1 is actu-.

ated, with the movement of the printing belt 4 the idle pulley 3 isrotated at a surface speed synchronized with the speed of the printingbelt 4 and the rotation force of the idle pulley 3 is transmitted to thedrive shaft 45 through the gearing mechanism'comprising members 39, 40,41, 42, 43 and 44. Then, by the engagement be belt 4. When the drivemeans such as illustrated in FIGS. 1-A and 1-B is used, even whenslippage occurs between the drive pulley 2 and the printing belt 4, itis possible to drive and rotate the rotary screens 14 at a speedsynchronized completely with the speed of the printing belt 4, becausethe load imposed between the idle pulley 3 and the printing belt 4 issmaller than the load imposed between the drive pulley 2 and theprinting belt 4 and hence, the frequency of occurrence of slippagebetween the idle pulley 3 and the printing belt 4 is much lower than thefrequency of occurrence of slippage between the drive pulley 2 and theprinting belt 4. Further, the rotation of the rotary screens 14 by theidle pulley 3 is not influenced by unevenness of the elongation of theprinting belt 4. The change of the diameter of the rotary screens 14,i.e., the change of the design size, may be accomplished easily byexchanging the change gear 41. It is preferred that the idle pulley 40be mounted oscillatably around the shaft 38 in engagement with the drivespur gear 39, so that a change gear 41 suitable for attaining a screensynchronized with the speed of the printing belt can be readilyattached.

In FIGS. 1-A and 1-B, to the other end of the screendriving shaft 36 isconnected a motor 45 equipped with a reduction gear for driving androtating the rotary screen independently through the magnetic or otherknown clutch M2. When the above-explained first clutch M1 is notactuated and the second clutch M2 is actuated, the screen-driving shaft36 is driven and rotated by the motor 48 equipped with a reduction gear,and the rotary screens 14 are then driven and rotated by means of thegearing mechanism comprising members 37, 35, 34, 32 and 31.

The printing operation with use of the printing machine of thisinvention is conducted in the following manner. In FIGS. l-A and 1-B,the first clutch M1 is actuated and the second clutch M2 is notactuated. By operation of the drive motor M, the drive pulley 2 isdriven and rotated, and with the rotation of the pulley 2, the endlessbelt 4 for printing is driven. The material 10 to be printed passes overguide rollers 12 and is fed between a pressure roller 11 and theprinting belt 4 travelling on an idle pulley 3. The material 10 is fedonto the upper surface of the printing belt 4 and continuously forwardedto the printing operation zone. With the rotation of the idle pulley 3,the drive shaft 45 is driven and rotated, which results in rotation ofthe rotary screens 14 at a speed synchronized with the speed of theprinting belt 4. At this time, the lift frame 22 is in the lowermostposition as illustrated in FIG. 2-A and the rotary screens 14 contactthe material 10 on the printing belt 4. The squeegee member 15 contactsthe inner surface of each rotary screen 14 and it causes a printing inkor paste fed into the interior of the rotary screen 14 to ooze outthrough the screen onto the material 10 to be printed which is on theprinting belt 4. Thus, the printing of the material 10 is accomplished.The material 10 which has been printed is separated from the printingbelt 4 on the discharge side of the printing belt 4, and is forwardedthrough a guide roller 13 to the subsequent treatment zone, forinstance, the drying or winding zone. After passage through the drivepulley 2, the endless belt 4 for printing is subjected to suchtreatments as surface washing and drying and comes to the position ofthe idle pulley 3, following which the above operation procedures arerepeated.

Initiation of the printing operation may be effected while maintainingthe rotary screens 14 at the position illustrated in FIGS. l-A and 2-A.In order to prevent wear of the rotary screens 14 at the time ofinitiation of the printing operation, however, it is preferred toinitiate the operation by maintaining the rotary screens 14 at theposition illustrated in FIGS. 1-8 and 2-B and lowering the rotaryscreens 14 coincidentally with initiation of driving of the printingbelt 4.

At the time of stoppage of the printing operation, a fluid is introducedinto the fluid cylinder 29, and the racks 23 and, in turn, the liftframe 22 are lifted as illustrated in FIG. 2-B. With the lifting of theframe 22, the rotary screens 14 are rotated upwardly around thesupporting shaft 18 and separate from the material to be printed whichis on the printing belt 4. Also with the lifting of the lift frame 22,the end of each of the squeegees parts from the inner surface of thescreen 14. Coincidentally with rising of the lift frame 22, theoperation of the drive motor M for driving the printing belt 4 isstopped, and disengagement of the first clutch M1 and engagement of thesecond clutch M2 are simultaneously effected. As a result, thescreen-driving shaft 36 is driven and rotated by the motor 48 throughthe reduction gear, and the rotary screens 14 are driven and rotatedindependently of the printing belt 4 by means of the gearing mechanismcomprising members 37, 35, 34 32 and 31.

According to this invention, as described hereinabove, at the time oftermination of the printing operation, the rotary screen 14 is liftedfrom the printing operation position (shown in FIGS. l-A and 2-A) to theraised position shown in FIGS. 1-8 and 2-B, and at this risen positionthe rotary screen 14 can be driven and rotated independently of theprinting belt 4, whereby an undesired phenomenon that at the time ofstoppage of the printing operation the printing paste or ink flows outthrough the screen onto the material to the printed or the printing beltcan be effectively prevented.

I claim:

1. A rotary screen printing machine comprising pulleys at opposite endsof a printing operation zone, at least one pulley being a driven pulley,a printing belt supported on and driven by said pulleys for supporting amaterial to be printed and transporting it through the printingoperation zone, at least one rotary screen positioned above said belt insaid printing operation zone, a squeegee member in the interior of saidrotary screen for squeezing a printing paste or ink through the rotaryscreen onto the material to be printed, a first drive mechanism fordriving the rotary screen at a speed synchronized with the speed of theprinting belt, a bearing device on which the rotary screen is rotatablymounted, a supporting member on which said bearing device is mounted asupporting shaft on which one end of said supporting member is pivotallymounted, a lifting device to which the other end of said supportingmember is attached, a screen gear on the rotary screen, an idle gear onsaid supporting shaft engaged with said screen gear, a screen drivinggear engaged with said idle gear,

a second drive mechanism independent of said first drive mechanism, andmeans alternatively connecting said screen driving gear with said firstdrive mechanism and said second drive mechanism, whereby when theprinting operation is stopped, the rotary screen can be raised from theprinting operation position by said lifting device and in the raisedposition the rotary screen can be driven and rotated independently ofthe printing belt.

2. A rotary screen printing machine as claimed in claim 1 wherein saidlastmentioned means comprises a screen driving shaft, a gearingmechanism coupled between said screen driving shaft and said screendriving gear, and means at the ends of said screen driving shaft forcoupling said screen driving shaft to said first and second drive means,respectively.

3. A rotary screen printing mechanism as claimed in claim 2 wherein themeans for connecting the screen driving shaft to said first drivemechanism is a first clutch mechanism at one end of said screen drivingshaft, and said means for connecting the screen driving shaft to thesecond drive mechanism is a second clutch mechanism, said first drivemechanism comprising a gearing mechanism coupled to one of said pulleysfor and belt for transmitting the rotation of said pulley, and a driveshaft coupled between said gearing mechanism and said first clutchmechanism for transmitting the rotation of said drive shaft through thefirst clutch mechanism to said screen driving shaft.

4. A rotary screen printing machine as claimed in claim 1 in which saidscreen gear is on one end of said rotary screen, and said machinefurther comprises a further screen gear on the other end of said rotaryscreen, a shaft rotatably mounted on said lifting device, and first spurgear fixed on one end of said shaft and engaged with said firstmentionedscreen gear, and a second spur gear on the other end of said shaftengaged with said further screen gear.

5. A rotary screen printing machine as claimed in claim 1, in which saidlifting device comprises a vertical member on which said supportingmember is mounted, a vertically movable lift frame on which saidvertical member is mounted, and a fluid pressure actuated means coupledto said lift frame for raising and lowering said lift frame.

6. A rotary screen printing machine as claimed in claim 5 in which saidsqueegee member is mounted on said lift frame and positioned within saidrotary screen so that when the rotary screen is in contact with thematerial to be printed the blade of said squeegee member is in contactwith the inner surface of the rotary screen, and when the rotary screenis in the raised position, the blade of the squeegee member is spacedfrom the inner surface of the rotary screen.

7. A- rotary screen printing machine as claimed in claim 1 in whichthere are a plurality of rotary screens each having an associatedsqueegee member, bearing device, supporting member, lifting devicescreen gear,

idle gear and screen driving gear.

1. A rotary screen printing machine comprising pulleys at opposite endsof a printing operation zone, at least one pulley being a driven pulley,a printing belt supported on and driven by said pulleys for supporting amaterial to be printed and transporting it through the printingoperation zone, at least one rotary screen positioned above said belt insaid printing operation zone, a squeegee member in the interior of saidrotary screen for squeezing a printing paste or ink through the rotaryscreen onto the material to be printed, a first drive mechanism fordriving the rotary screen at a speed synchronized with the speed of theprinting belt, a bearing device on which the rotary screen is rotatablymounted, a supporting member on which said bearing device is mounted asupporting shaft on which one end of said supporting member is pivotallymounted, a lifting device to which the other end of said supportingmember is attached, a screen gear on the rotary screen, an idle gear onsaid supporting shaft engaged with said screen gear, a screen drivinggear engaged with said idle gear, a second drive mechanism independentof said first drive mechanism, and means alternatively connecting saidscreen driving gear with said first drive mechanism and said seconddrive mechanism, whereby when the printing operation is stopped, therotary screen can be raised from the printing operation position by saidlifting device and in the raised position the rotary screen can bedriven and rotated independently of the printing belt.
 2. A rotaryscreen printing machine as claimed in claim 1 wherein said lastmentionedmeans comprises a screen driving shaft, a gearing mechanism coupledbetween said screen driving shaft and said screen driving gear, andmeans at the ends of said screen driving shaft for coupling said screendriving shaft to said first and second drive means, respectively.
 3. Arotary screen printing mechanism as claimed in claim 2 wherein the meansfor connecting the screen driving shaft to said first drive mechanism isa first clutch mechanism at one end of said screen driving shaft, andsaid means for connecting the screen driving shaft to the second drivemechanism is a second clutch mechanism, said first drive mechanismcomprising a gearing mechanism coupled to one of said pulleys for andbelt for transmitting the rotation of said pulley, and a drive shaftcoupled between said gearing mechanism and said first clutch mechanismfor transmitting the rotation of said drive shaft through the firstclutch mechanism to said screen driving shaft.
 4. A rotary screenprinting machine as claimed in claim 1 in which said screen gear is onone end of said rotary screen, and said machine further comprises afurther screen gear on the other end of said rotary screen, a shaftrotatably mounted on said lifting device, and first spur gear fixed onone end of said shaft and engaged with said firstmentioned screen gear,and a second spur gear on the other end of said shaft engaged with saidfurther screen gear.
 5. A rotary screen printing machine as claimed inclaim 1, in which said lifting device comprises a vertical member onwhich said supporting member is mounted, a vertically movable lift frameon which said vertical member is mounted, and a fluid pressure actuatedmeans coupled to said lift frame for raising and lowering said liftframe.
 6. A rotary screen printing machine as claimed in claim 5 inwhich said squeegee member is mounted on said lift frame and positionedwithin said rotary screen so that when the rotary screen is in contactwith the material to be printed the blade of said squeegee member is incontact with the inner surface of the rotary screen, and when the rotaryscreen is in the raised position, the blade of the squeegee member isspaced from the inner surface of the rotary screen.
 7. A rotary screenprinting machine as claimed in claim 1 in which there are a plurality ofrotary screens each having an associated squeegee member, bearingdevice, supporting member, lifting device screen gear, idle gear andscreen driving gear.